1. Field of the Invention
Aspects of the present invention relate to a protection circuit module and a battery pack using the same, and more particularly, to a protection circuit module and a battery pack using the same having a small printed circuit board area, being resistant to electromagnetic waves or static electricity, and having reduced cost achieved by integrating an integrated circuit (IC), a charging switch, and a discharging switch in one semiconductor package.
2. Description of the Related Art
In general, lithium-type secondary batteries are high in energy density when compared with those of conventional nickel-cadmium and nickel-hydride batteries. Examples of lithium-type secondary batteries include lithium ion batteries and lithium ion polymer batteries. Lithium-type secondary batteries are mainly used as a power source of portable electronic devices such as a notebook computer, a mobile phone, and a personal digital assistant (PDA).
However, if lithium-type secondary batteries are used in an inappropriate manner, there is a high probability that they explode or spontaneously combust because of their unstable chemical components. Accordingly, what is referred to as a “Protection Circuit Module” is mounted on the lithium-type secondary batteries in order to protect the batteries from being overcharged and over-discharged, and in order to prevent a drop in the performance thereof.
FIGS. 1A and 1B illustrate an outline of a related art protection circuit module. As illustrated, the related art protection circuit module 100′ includes a plate-type printed circuit board 110′, an integrated circuit 120′, a charging switch 130′, a discharging switch 140′, a plurality of passive elements 151′ and 152′, and conductive pads 161′ and 162′. As illustrated, the integrated circuit 120′ is of a one semiconductor-package type, and senses the voltage and the current of a secondary battery (not shown), and thereby turns on or off the charging switch 130′ and the discharging switch 140′. Further, the charging switch 130′ and the discharging switch 140′ are of a one semiconductor-package type, respectively. The integrated circuit 120′ and the charging switch 130′, and the integrated circuit 120′ and the discharging switch 140′, are coupled to each other through a wiring pattern formed on the printed circuit board 110′. Further, the charging switch 130′ and the discharging switch 140′ can be a Power MOSFET.
Referring to FIG. 2, illustrated is a circuit diagram of the related art battery pack that includes the related art protection circuit module. As illustrated, the related art battery pack 200′ includes a secondary battery 210′, pack terminals 171′ and 172′, a resistor 151′, a capacitor 152′, an integrated circuit 120′, a charging switch 130′, and a discharging switch 140′. The charging switch 130′ and the discharging switch 140′ are electrically coupled to the integrated circuit 120′ by the wiring pattern 111′. Accordingly, the charging switch 130′ and the discharging switch 140′ can be turned on or off by a control signal of the integrated circuit 120′. Further, a charger or an outside system is electrically coupled to the pack terminals 171′ and 172′.
In the related art battery pack 200′, the integrated circuit 120′ senses the charging voltage or the discharging voltage of the secondary battery 210′. For example, if the secondary battery 210′ is overcharged, the integrated circuit 120′ outputs a predetermined control signal to the charging switch 130′. Accordingly, the charging switch 130′ is turned off, to thereby prevent additional charging. Further, if the secondary battery 210′ is over-discharged, the integrated circuit 120′ outputs a predetermined control signal to the discharging switch 140′. Accordingly, the discharging switch 140′ is turned off to thereby prevent additional discharging.
A parasitic diode is formed in the charging switch 130′ and the discharging switch 140′, respectively. Hence, if the charging switch 130′ is turned off by the overcharging of the secondary battery 210′, the secondary battery 210′ goes to a dischargeable state. Further, if the discharging switch 140′ is turned off by the over-discharging of the secondary battery 210′, the secondary battery 210′ goes to a chargeable state.